NZ618857B2 - Ceramic particle mixture, and method for manufacturing ceramic parts from such a mixture - Google Patents
Ceramic particle mixture, and method for manufacturing ceramic parts from such a mixture Download PDFInfo
- Publication number
- NZ618857B2 NZ618857B2 NZ618857A NZ61885712A NZ618857B2 NZ 618857 B2 NZ618857 B2 NZ 618857B2 NZ 618857 A NZ618857 A NZ 618857A NZ 61885712 A NZ61885712 A NZ 61885712A NZ 618857 B2 NZ618857 B2 NZ 618857B2
- Authority
- NZ
- New Zealand
- Prior art keywords
- ceramic
- green
- mixture
- laser radiation
- particles
- Prior art date
Links
- 239000000919 ceramic Substances 0.000 title claims abstract description 88
- 239000002245 particle Substances 0.000 title claims abstract description 66
- 239000000203 mixture Substances 0.000 title claims abstract description 59
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 10
- 238000003754 machining Methods 0.000 claims abstract description 62
- 229910010293 ceramic material Inorganic materials 0.000 claims abstract description 39
- 230000002745 absorbent Effects 0.000 claims abstract description 26
- 239000002250 absorbent Substances 0.000 claims abstract description 26
- 229910003480 inorganic solid Inorganic materials 0.000 claims abstract description 20
- 239000011343 solid material Substances 0.000 claims abstract description 19
- 238000010521 absorption reaction Methods 0.000 claims abstract description 11
- 238000007493 shaping process Methods 0.000 claims abstract description 11
- 239000000654 additive Substances 0.000 claims abstract description 9
- 230000000996 additive Effects 0.000 claims abstract description 9
- 239000007787 solid Substances 0.000 claims abstract description 5
- 229910010272 inorganic material Inorganic materials 0.000 claims abstract description 4
- 239000011147 inorganic material Substances 0.000 claims abstract description 4
- 239000000463 material Substances 0.000 claims description 31
- 238000005245 sintering Methods 0.000 claims description 18
- 239000000725 suspension Substances 0.000 claims description 10
- 238000003379 elimination reaction Methods 0.000 claims description 7
- 238000001125 extrusion Methods 0.000 claims description 5
- 239000000843 powder Substances 0.000 claims description 5
- 238000005266 casting Methods 0.000 claims description 3
- 230000015556 catabolic process Effects 0.000 claims description 3
- 230000004059 degradation Effects 0.000 claims description 3
- 238000006731 degradation reaction Methods 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims description 3
- 239000006194 liquid suspension Substances 0.000 claims description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 32
- 229910002804 graphite Inorganic materials 0.000 abstract description 11
- 239000010439 graphite Substances 0.000 abstract description 11
- 239000003575 carbonaceous material Substances 0.000 abstract 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N AI2O3 Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 17
- 229910052799 carbon Inorganic materials 0.000 description 16
- 239000011230 binding agent Substances 0.000 description 15
- 238000000034 method Methods 0.000 description 11
- 239000007788 liquid Substances 0.000 description 10
- 238000010438 heat treatment Methods 0.000 description 9
- GFQYVLUOOAAOGM-UHFFFAOYSA-N Zirconium(IV) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 description 7
- 229910052845 zircon Inorganic materials 0.000 description 7
- 229910052846 zircon Inorganic materials 0.000 description 7
- 238000009834 vaporization Methods 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 239000003570 air Substances 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- 239000002360 explosive Substances 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 238000004108 freeze drying Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000010348 incorporation Methods 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 229920001223 polyethylene glycol Polymers 0.000 description 3
- 230000035882 stress Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 238000005553 drilling Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000003628 erosive Effects 0.000 description 2
- 230000001747 exhibiting Effects 0.000 description 2
- 238000005755 formation reaction Methods 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- 238000003801 milling Methods 0.000 description 2
- 239000011812 mixed powder Substances 0.000 description 2
- 239000012074 organic phase Substances 0.000 description 2
- 230000002829 reduced Effects 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 238000003826 uniaxial pressing Methods 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- JRPBQTZRNDNNOP-UHFFFAOYSA-N Barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 1
- 241000218378 Magnolia Species 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N TiO Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- QORWJWZARLRLPR-UHFFFAOYSA-H Tricalcium phosphate Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 description 1
- 239000003830 anthracite Substances 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- 229910002113 barium titanate Inorganic materials 0.000 description 1
- 239000000316 bone substitute Substances 0.000 description 1
- 239000001506 calcium phosphate Substances 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 229910052878 cordierite Inorganic materials 0.000 description 1
- 230000000875 corresponding Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000003247 decreasing Effects 0.000 description 1
- 230000002939 deleterious Effects 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 239000002274 desiccant Substances 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- 230000005662 electromechanics Effects 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229910052588 hydroxylapatite Inorganic materials 0.000 description 1
- 230000001771 impaired Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910052451 lead zirconate titanate Inorganic materials 0.000 description 1
- 230000000670 limiting Effects 0.000 description 1
- 238000011068 load Methods 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 238000003913 materials processing Methods 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- 238000005459 micromachining Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006011 modification reaction Methods 0.000 description 1
- 229910002119 nickel–yttria stabilized zirconia Inorganic materials 0.000 description 1
- 230000003287 optical Effects 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000036961 partial Effects 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 230000002035 prolonged Effects 0.000 description 1
- 238000002310 reflectometry Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 229910002082 tetragonal zirconia polycrystal Inorganic materials 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 229910001929 titanium oxide Inorganic materials 0.000 description 1
- 238000000844 transformation Methods 0.000 description 1
- 230000001131 transforming Effects 0.000 description 1
- 229940078499 tricalcium phosphate Drugs 0.000 description 1
- 229910000391 tricalcium phosphate Inorganic materials 0.000 description 1
- 235000019731 tricalcium phosphate Nutrition 0.000 description 1
- KNXVOGGZOFOROK-UHFFFAOYSA-N trimagnesium;dioxido(oxo)silane;hydroxy-oxido-oxosilane Chemical compound [Mg+2].[Mg+2].[Mg+2].O[Si]([O-])=O.O[Si]([O-])=O.[O-][Si]([O-])=O.[O-][Si]([O-])=O KNXVOGGZOFOROK-UHFFFAOYSA-N 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K2101/00—Articles made by soldering, welding or cutting
- B23K2101/18—Sheet panels
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K2103/00—Materials to be soldered, welded or cut
- B23K2103/50—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
- B23K2103/52—Ceramics
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/0006—Working by laser beam, e.g. welding, cutting or boring taking account of the properties of the material involved
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/062—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam
- B23K26/0622—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses
- B23K26/0624—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses using ultrashort pulses, i.e. pulses of 1ns or less
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/08—Devices involving relative movement between laser beam and workpiece
- B23K26/082—Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/352—Working by laser beam, e.g. welding, cutting or boring for surface treatment
- B23K26/355—Texturing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/36—Removing material
- B23K26/362—Laser etching
- B23K26/364—Laser etching for making a groove or trench, e.g. for scribing a break initiation groove
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/36—Removing material
- B23K26/40—Removing material taking account of the properties of the material involved
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B11/00—Apparatus or processes for treating or working the shaped or preshaped articles
- B28B11/12—Apparatus or processes for treating or working the shaped or preshaped articles for removing parts of the articles by cutting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B17/00—Details of, or accessories for, apparatus for shaping the material; Auxiliary measures taken in connection with such shaping
- B28B17/0036—Cutting means, e.g. water jets
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3217—Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
- C04B2235/3225—Yttrium oxide or oxide-forming salts thereof
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/42—Non metallic elements added as constituents or additives, e.g. sulfur, phosphor, selenium or tellurium
- C04B2235/422—Carbon
- C04B2235/425—Graphite
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
- C04B2235/54—Particle size related information
- C04B2235/5418—Particle size related information expressed by the size of the particles or aggregates thereof
- C04B2235/5445—Particle size related information expressed by the size of the particles or aggregates thereof submicron sized, i.e. from 0,1 to 1 micron
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/60—Aspects relating to the preparation, properties or mechanical treatment of green bodies or pre-forms
- C04B2235/604—Pressing at temperatures other than sintering temperatures
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
- C04B2235/66—Specific sintering techniques, e.g. centrifugal sintering
- C04B2235/665—Local sintering, e.g. laser sintering
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
- C04B2235/94—Products characterised by their shape
- C04B2235/945—Products containing grooves, cuts, recesses or protusions
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
- C04B2235/95—Products characterised by their size, e.g. microceramics
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/03—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite
- C04B35/04—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite based on magnesium oxide
- C04B35/053—Fine ceramics
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
- C04B35/111—Fine ceramics
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Abstract
Disclosed is a method for manufacturing ceramic parts comprising: implementation of a ceramic particle mixture, as components, a predominant portion by weight of sinterable particles made of a ceramic material and an additive being a solid inorganic material (e.g., carbon based material such as graphite), wherein said inorganic solid material is absorbent for laser radiation emitting a predetermined energy flow at a predetermined wavelength, and at this wavelength has a specific absorptivity greater than that of the other components of the ceramic mixture, in that said ceramic mixture contains the particles of absorbent inorganic solid matter in the dispersed state, in proportions of less than 5 % by weight and more than 0 % by weight of the dry mixture, and in that the method further comprises; green shaping of this ceramic mixture and obtaining a dry green ceramic blank; green machining of the green ceramic blank, by removal of ceramic material by its exposure to said pulsed laser radiation emitting a predetermined energy flow at said predetermined wavelength, and; during said exposure to this laser radiation, direct selective absorption of the laser radiation energy by the particles of absorbent dispersed inorganic solid material which degrade abruptly, with gaseous emission, local dislocation of ceramic material from the green ceramic blank, ejection of this dislocated ceramic material and obtaining a machined ceramic part in the green state. hite), wherein said inorganic solid material is absorbent for laser radiation emitting a predetermined energy flow at a predetermined wavelength, and at this wavelength has a specific absorptivity greater than that of the other components of the ceramic mixture, in that said ceramic mixture contains the particles of absorbent inorganic solid matter in the dispersed state, in proportions of less than 5 % by weight and more than 0 % by weight of the dry mixture, and in that the method further comprises; green shaping of this ceramic mixture and obtaining a dry green ceramic blank; green machining of the green ceramic blank, by removal of ceramic material by its exposure to said pulsed laser radiation emitting a predetermined energy flow at said predetermined wavelength, and; during said exposure to this laser radiation, direct selective absorption of the laser radiation energy by the particles of absorbent dispersed inorganic solid material which degrade abruptly, with gaseous emission, local dislocation of ceramic material from the green ceramic blank, ejection of this dislocated ceramic material and obtaining a machined ceramic part in the green state.
Description
Ceramic particle mixture, and method for manufacturing ceramic parts from such a
mixture
The present invention relates to a ceramic particle mixture containing, as components, a
predominant portion by weight of sinterable particles made of a ceramic material and
particles of at least one additive, at least one of said at least one additive being a solid
inorganic material. The invention also relates to a ceramic blank and to a ceramic part in the
green or sintered state, on the basis of such a ceramic particle mixture, and to a method for
manufacturing ceramic parts from this ceramic mixture.
The process of laser machining by erosion is described by Pham D.T. et coll. in Laser
milling, Proc lnstn Mech Engrs, Vol. 216 Part B: J. Engineering Manufacture, p.657-667
(2002). For the machining, the laser irradiation is typically delivered in very brief periods of
time on surfaces of reduced dimensions. This results in extremely high peak power densities
12 2
(10 W/m ) which generate a series of transformations in the irradiated material.
The melting and the vaporisation of the material can be obtained in this way, which creates a
machining microcavity locally. The creation, little by little, of a series of such cavities (by
virtue in particular of a galvanometric deflector or the movement of motorised spindles)
makes it possible to structure the topography of the surface and to progressively reproduce
a complex shape. However, this process, well known by the name of "laser milling”, suffers
from a number of handicaps:
- In order for the process to be effective, the material must be absorbent for the
wavelength of the laser beam, which requires the laser source to be adapted to the
material to be machined.
- The machining times can be very long (several dozen hours), even for small or
limited volumes of eliminated material (several dozen mm for example).
- The heating produced by the beam in the part generates a "thermally affected zone"
where the properties of the material are locally impaired (formation of a vitreous
phase, cracking, creation of undesirable new phases,...). This aspect is particularly
critical for ceramic materials, which are considered very fragile, and for which the
generation of cracks for example is particularly deleterious from the point of view of
their mechanical stability.
Because of these limitations this method is often reserved for the manufacture of single
components and in very small quantities (stamping dies, structuring of moulds...).
In the Patent Application a method is described for machining a green
body from a stream of material or of energy such as a laser. The proposed machining is
carried out on a green ceramic or metal part consisting of an assembly of grains held
together by an organic binder. The shaping of the green part is obtained by a conventional
process of powder metallurgy also used by ceramicists and widely documented in the
literature (pressing, extrusion, etc...). The incorporation of a binder is likewise known in the
prior art which makes it possible to improve the cohesion of the granular assembly. The
machining described in this prior-art document is obtained by successive cuts or “slicings" of
the green object by the stream of energy or of material.
The patent application DE 19501279 discloses the use of a UV pulsed laser in order to
obtain a selective elimination of material.
However, this document emphasises that only limited removal of material is possible by this
technique by virtue of the rapid formation of a layer of molten material which is redeposited
at the surface. In response to this drawback the document offers the solution of machining
the surface in the presence of a fluid in order to avoid this redeposition of the removed
material.
In A. Kruusing, Underwater and water-assisted laser processing: Part 1 - general features,
steam cleaning and shock processing Optics and Lasers in Engineering 41 (2004), p.307-
327, the use of laser surface machining in the presence of a liquid film (often water) is
likewise described. During the laser irradiation the liquid film is locally heated abruptly and
evaporates explosively, ejecting the slag and the molten particles from the surface of the
material.
In the international patent application the principle of machining in a liquid
medium is extended to the case of green ceramic or metal components. The machining is
performed on granular assemblies of metal or of ceramic (held together by an organic
binder) which are immersed in a fluid (water or alcohol) and/or of which the surface is
sprayed by such a fluid. Variable periods of immersion (of ½ hour to 24 hours) are required
in order to enable the intrusion of the liquid to the core of the green part via its open porosity.
During the laser irradiation very rapid heating of the liquid contained in the green material
occurs at the surface of this material. The extremely rapid vaporisation of said liquid
(“explosive vaporisation") leads to the local bursting of the structure of the green part. The
method was implemented with success on certain ceramic materials (alumina and steatite)
but it is incapable of machining cordierite for example. The authors point out that all
ceramics are not adapted to this type of machining. Furthermore, the machined depths
remain small (less than 1 mm typically) since the diffuse heating of the part quickly causes
undesirable evaporation of the liquid. Continuing with this machining requires renewed
immersion of the part or continuous spraying of the liquid onto the surface to be machined.
The method appears particularly onerous to implement for at least three reasons:
The rapid evaporation of the solvent limits the machining depths to a fraction of a mm. The
method is not applicable to certain ceramic materials. It is necessary to machine the
components immediately after their emergence, as intermediate storage should be excluded
in view of the natural evaporation of the liquid used.
The patent application US 2010/0032417 mentions green machining by UV laser
(wavelength less than 400 nm) for the stripping/cleaning of “solder pad" or the drilling of
holes in devices intended for microelectronics. One embodiment provides a method of
machining by explosive vaporisation of the organic binder present in the green mass. The
organic vapours at high temperature expand at high speed and break down the green
material locally by ejecting matter. In this document, the organic phase which enables the
green machining is the binder well known to ceramicists which makes it possible to ensure
the cohesion of the grains with one another and increases the mechanical resistance of the
part.
In J. Gurauskis et coll., Laser drilling of Ni-YSZ Cements, Journal of the European Ceramic
Society 28(2008), p. 2673-2680, the authors describe in detail the procedure of laser
perforation of a green ceramic part. The particles of ceramic material absorb the laser
radiation, which causes their temperature to rise rapidly. Heat is then transferred to the
organic binder which pyrolises, producing a jet of gas. The gaseous explosion entrains with
it the matter which surrounds the treatment site.
A comparable method is described in Kamran Imen et al., Pulse CO Laser Drilling of Green
Alumina Ceramic, IEEE Transactions on Advanced Packaging, Vol. 22, no. 4, November
1999. The exposure to the laser radiation is effected here under pressure.
This examination of the prior art shows that in the case of methods of machining by erosion
under the effect of laser radiation of a green ceramic part shaped from a ceramic particle
mixture there is always a rapid heating of the particles of ceramic material. This heating is
used to advantage in order to vaporise a liquid phase which, simultaneously, is intended to
protect the ceramic material from excessive heating, or in order to pyrolise in the form of a
gaseous jet the organic binder which keeps the ceramic particles together.
The ceramic materials are not particularly adapted to absorb laser radiation in the
wavelengths between 200 nm and 3 μm. The absorptivity of the ceramic materials, in
particular of the oxide type, is often mediocre in this wavelength range. Any laser radiation
emitting in this range must therefore be sufficiently powerful and prolonged so that the
transfer of heat from the energy absorbed by the ceramic material to the liquid phase or to
the binder has the effect of explosive vaporisation of these phases accompanied by a
tearing of material. This results in the danger that partial melting of the ceramic particles
occurs during a poorly controlled process, which should be avoided, and a certain slowness
in the machining process. In addition, in the case where organic binder polymer is used, this
latter has the drawback of uncontrolled creep and melting in the thermally affected zone.
Moreover, in a wavelength range extending beyond 3 μm (far infrared) the absorptivity of the
ceramic material as well as that of the binder or of the liquid phase are considerably higher,
which leads to combined heating of the two materials and to the drawbacks mentioned
above.
Ceramic mixtures are also known which contain a large quantity of combinations of
porogenic agents, one of which may be formed of carbon. These mixtures are shaped and
fired, in particular in order to produce porous systems for treatment of exhaust gases from
cars (see US 2007/0006561) and they do not undergo any green machining by laser
treatment.
It would therefore be desirable to develop a ceramic particle mixture which enables green
machining of ceramic parts having complex shapes from simple shapes. This machining
should be very flexible and very quick to carry out, without exhibiting the drawbacks of
treatments according to the prior art.
A first aspect of the present invention provides a method of manufacturing ceramic parts
comprising implementation of a ceramic particle mixture according to the invention containing,
as components, a predominant portion by weight of sinterable particles made of a ceramic
material and particles of at least one additive, at least one of said at least one additive being a
solid inorganic material.
In the method according to the invention, said inorganic solid material is absorbent for laser
radiation emitting a predetermined energy flow at a predetermined wavelength, and at this
wavelength has a specific absorptivity greater than that of the other components of the
ceramic mixture, said ceramic mixture containing the particles of absorbent inorganic solid
matter in the dispersed state, in proportions of less than 5 % by weight and more than 0 % by
weight of the dry mixture. The method according to the invention further comprises
- green shaping of this ceramic mixture and obtaining a dry green ceramic blank,
- green machining of the green ceramic blank, by removal of ceramic material, by its
exposure to said pulsed laser radiation emitting a predetermined energy flow at said
predetermined wavelength, and- during said exposure to this laser radiation, direct
selective absorption of the laser radiation energy by the particles of absorbent
dispersed inorganic solid material which degrade abruptly, with gaseous emission,
local dislocation of ceramic material from the green ceramic blank, ejection of this
dislocated ceramic material and obtaining a machined ceramic part in the green state.
In order to produce the ceramic particle mixture, the components thereof, and therefore of
necessity the particles of the ceramic material(s) and of the absorbent dispersed inorganic
solid material, can be mixed by dry means, which gives a dry powder. It is also possible to
mix them by liquid means by putting the components in suspension. In this case provision
may be made for drying the mixture in suspension in a known manner, for example in an
oven, a furnace, by freeze-drying or atomisation, before the shaping, in order likewise to
obtain a dry powder for the shaping.
Advantageously the green shaping is performed by techniques known to the person skilled in
the art, for example by extrusion, casting or pressing. In the case of extrusion or casting, the
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ceramic mixture is implemented in the form of a paste or a suspension and, in this case, the
step of drying indicated above is then performed after the shaping. In all cases a dry green
ceramic blank is obtained which is intended for machining.
After shaping of this dry green ceramic blank, the green mass can be readily machined by
laser. The laser radiation is pulsed and can originate from any appropriate laser source
emitting in the UV, IR or the visible range. The laser radiation may advantageously have a
wavelength of 200 nm to 3 µm, in particular 900 nm to 1100 nm. Pulse durations less than
150 ns may preferably be provided. When machining takes place in the presence of an
oxidising atmosphere the absorbent dispersed solid material exposed to the laser radiation
can be oxidised in the form of a gas. In a particularly advantageous manner, machining may
take place at ambient pressure, in air.
The method may also comprise, after green machining, sintering of the particles of ceramic
material of the green machined ceramic part. The sintering temperature will depend upon the
nature of the particles of ceramic material.
Provision may advantageously be made, before the sintering, for elimination of the absorbent
dispersed inorganic solid material outside the green machined ceramic part by thermal stress
thereon at a degradation temperature of this material. In this case, the sintered ceramic part
is totally devoid of ADSM, like the sintered ceramic parts according to the prior art, but without
exhibiting the defects of the latter, such as microcracks, deposit of vitreous material, etc.
Another aspect of the present invention provides a ceramic particle mixture such as indicated
at the beginning. In this mixture, said inorganic solid material is absorbent for laser radiation
emitting a predetermined energy flow at a predetermined wavelength, and at this
predetermined wavelength has a specific absorptivity greater than that of the other
components of the ceramic mixture, and said ceramic mixture contains the particles of
absorbent inorganic solid matter in the dispersed state, in proportions of less than 5 % and
more than 0 % by weight of the dry mixture, the particles of absorbent inorganic solid matter
being degradable abruptly, with gaseous emission, in the presence of said laser radiation.
In the event of exposure of this ceramic particle mixture to the above-mentioned laser
radiation, these are not therefore sinterable particles of ceramic material which will directly
and preferentially absorb the energy flow, but particles of a mineral additive selected for this
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purpose which will be referred to below as absorbent dispersed solid material ADSM. These
particles touched by the laser radiation can degrade in gaseous form in extremely short
periods of time, in particular less than a microsecond. In particular, pulsed lasers of the
nanosecond type (pulsation durations below 150 ns) emitting in the vicinity of 1 µm and of
average power (typically from 5 to 100 W of average power) are very appropriate for this
purpose. Any risk of untimely heating, even local, of the surrounding ceramic material is thus
avoided and the machining times can be very short.
The coefficient of absorption A or absorptivity is a fundamental property governing the
interaction between an electromagnetic radiation and a surface affected by this latter. It is
given by:
A = 1-R
where R is the reflectivity of the surface of the irradiated material.
This quantity without units depends upon the wavelength of the incident radiation. It is
between 0 (no absorption) and 1 (complete absorption). (See: Ready J.F. (ed.), LIA
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handbook of laser materials processing, Laser Institute of America, Magnolia Publishing Inc.,
2001, as well as Oliveira C. et al., Etude de l'absorption du rayonnement IR en vue du
traitement laser d'alliages ferreux, J. Phys. III France, 2 (1992), 2203-2223).
By the incorporation of a mass fraction of ADSM of less than 5 % by weight of the dry
mixture two objectives are ensured: efficient machining as indicated above, but also the
most complete possible densification of the part to be machined, advantageously 100 % of
the theoretical density.
Preferably, in the ceramic particle mixture according to the invention the absorbent
dispersed inorganic solid material has, relative to the other components, an absorptivity
differential of the laser radiation which is greater than 0.2, advantageously equal to or
greater than 0.4, preferably equal to or greater than 0.5. Advantageously, the absorbent
dispersed solid material is a non-binding material. It should be noted that the ceramic
particle mixture according to the invention can contain, as another additive, at least one
binder for the particles of ceramic material. It is possible to envisage any type of binder
known in the art, in particular an organic binder which may be in the form of inherently sticky
particles distributed among the sinterable particles of ceramic material or coating these
particles. The content of organic binder incorporated in the mixture according to the
invention is preferably less than 5 % by weight of the dry mixture, in particular less than 3 %
by weight.
According to one embodiment of the invention, the absorbent dispersed solid material is
stable in the absence of thermal and/or optical stresses. The ceramic particle mixture can
therefore be stored without problems in normal conditions, in particular at ambient
temperature and in the absence of exposure to laser radiation. It can be in the form of a
powder, preferably totally dry, or a suspension of particles in a liquid suspension medium, for
example an aqueous medium, such as water. The ADSM is advantageously totally
degradable in controlled thermal conditions, higher than 400 °C. Thus after green machining
of the ceramic part shaped from the ceramic particle mixture it is possible to make any trace
of the absorbent dispersed inorganic solid material completely disappear before the step of
sintering the part.
According to the invention, the absorbent dispersed inorganic solid material may be totally or
at least partially carbon. Carbon may be advantageously chosen from among the group
consisting of graphite, anthracite, carbon black, activated charcoal, carbon nanotubes,
graphene foils and mixtures thereof. It is also possible to envisage an organic phase charged
with a dispersion of carbon, for example graphite or carbon black.
An ADSM of choice for the machining of green ceramic parts is carbon and its derivatives.
Carbon has a high coefficient of absorption or absorptivity in a wide range of frequencies
accessible to modern laser sources, in particular between 200 nm and 3 µm. Irradiated in
pulsed mode, carbon degrades violently with gaseous emission which bursts the structure of
the surrounding green material causing the ejection of particles of ceramic material. A
dispersion of carbon of micrometre or submicron dimension (d90 < 5 µm, preferably < 1 µm)
is advantageous since it enables excellent homogeneity of the green material. In general,
regardless of the nature of the dispersed ADSM, the smaller the size of its particles, the
smaller and better the homogeneity of the green material may be. The quantity of carbon
required for an effective green machining will likewise be less with a dispersion of smaller
particle size.
Carbon has the advantage of excellent absorption of laser energy in an extended range of
wavelengths (from UV to far IR) and it is therefore compatible with machining by pulsed laser
of the nanosecond type, for example excimer, Nd:YAG, Nd:YVO , fibre laser or the like. In the
wavelength range between 200 nm and 3 µm, the coefficient of absorption of carbon exceeds
the value of 0.7.
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The sinterable particles of ceramic material are preferably totally or at least partially of
ceramic material of the oxide type. As ceramic material, mention may be made in particular of
alumina, zircon, silica, magnesia, zinc oxide, titanium oxide, mixed oxides such as PZT,
barium titanate, silicates, hydroxyapatite, tricalcium phosphate and mixtures thereof.
The sinterable particles of ceramic material may advantageously have a micron or submicron
particle size.
The mass fraction of ADSM incorporated in the ceramic particle mixture according to the
invention may advantageously be between 1 % and 3 % by weight of the dry mixture.
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Aspects of the present invention also relates to ceramic blanks and to ceramic parts
machined in the green state which are based on a ceramic particle mixture according to the
invention. It also relates to the sintered ceramic parts obtained after sintering of ceramic parts
machined in the green state according to the invention. The invention also relates to a
method for manufacturing ceramic parts, both in the green state and in the sintered state,
from a ceramic particle mixture according to the invention.
The machined ceramic parts according to the invention may in particular be components
intended for electronics, electromechanics, for the biomedical field (dental prostheses, bone
substitutes, etc.), the manufacture of extrusion dies, jewellery, precision mechanics, filtration,
catalysis supports and the like.
The invention will now be described in greater detail with the aid of non-limiting examples.
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The appended Figures 2 and 5 illustrate machined parts according to the invention before
sintering, Figures 1, 4 and 6 show parts machined according to the invention after sintering
and Figure 3 shows a green machined part without ADSM.
Example 1
Green machining of a fine alumina by Nd :YVO laser
A defined quantity of alumina (P172SB from Pechiney) is weighed (100 g) and put in
suspension at natural pH in demineralised water (100 g). 1 % by mass of polyethylene glycol
PEG is added to the suspension (i.e. 1 g) in order to serve as organic binder. 23.5 g of an
aqueous suspension of a colloidal graphite (Aquadag 18 % - Acheson Industries Ltd) are
added to the suspension of alumina particles, everything is mixed for 30 minutes then dried
either by freeze-drying or with a rotary evaporator. Thus a dry mixture is obtained containing
4.2 % by weight of graphite relative to the total weight of the mixture. The graphite particles
have a particle size of d90 < 5 μm and the alumina particles have a particle size of d50 = 0.4
m.
The mixed powder thus obtained is shaped by uniaxial pressing (40 MPa applied to tablets
of 25 mm diameter), followed by isostatic post-compaction (170 MPa for 2 min).
The green blanks obtained in the form of tablets are then, at ambient pressure, machined by
laser from a Trumark commercial marking station (Trumpf) equipped with a solid Nd:YVO
laser of 20 W nominal power provided with a Q Switch, making it possible to work in pulsed
mode, of a motorised table XY and a galvanometric head enabling the beam to sweep over
the surface to be machined. The optics with a focal length of 163 mm enables a spot of 45
μm to be obtained. The optimum lasing parameters obtained on the basis of a parametric
study are 40 % - 80 % of nominal power, a working frequency of 40 - 80 kHz, a sweep
speed of 100 - 6000 mm/s, an interval between pulses of 1 to 5 μs and pulse durations
between 8 and 17 ns. The machining is performed based on a CAD file of format .dxf for
example.
The laser emits radiation having a wavelength of 1.06 μm. At this wavelength alumina has
an absorptivity of approximately 0.1 whilst that of carbon rises to about 0.9.
The results obtained, illustrated in Figure 1 after sintering, reveal the possibility of machining
finely perforated grids (hole diameter 100 μm spaced by 60 μm) at depths of the order of 1
mm and also very deep machining to depths easily exceeding 5 mm. The only limit identified
for the machining depth is given by the aspect ratio of hole width/depth which is close to
1/10 for the focusing optics used. The recorded rates of removal of material are of the order
of 10 - 100 mm per min.
The machined green parts are next heat treated in air in two steps: the first step seeks to
totally eliminate the residual carbon in the part; the second step relates to sintering the
alumina. A heat treatment cycle including a stage of 1 hour at 600 °C (rate of increase of 5
°C/min) followed by a stage at 1550 °C for 1 hour ( rate of increase of 5 °C/min) and finally a
lowering to ambient temperature (at 5 °C/min) makes it possible to obtain a perfectly dense
part, devoid of visible defects (pores or cracks). The machined surfaces observed under a
scanning electron microscope revealed no crack, no porosity, nor any layer of redeposited
molten material.
With this alumina, analogous comparative tests have been performed on green blanks with
and without ADSM. A machined green blank according to the invention is illustrated in
Figure 2. It has neat cavity edges and the bottoms of the cavities are perfectly clean. The
greyish colour of the blank is caused by the presence of graphite as ADSM. After sintering
and degradation of the graphite the part will have a colour identical to that obtained on the
blank of Figure 1. The green blanks without ADSM have revealed the possibility of
performing green machining (see Figure 3). However, peak powers higher than those
provided for the green machining with ADSM are then required (typically > 60 - 80 % of the
nominal power). Moreover, the rates of removal of material are much lower than those
obtained in the presence of ADSM (decreased by a factor 3 as a minimum). Likewise, the
depths which can be machined are much reduced and cannot exceed 2 mm: the grains of
alumina quickly start to sinter, or even to melt, under the effect of the power provided by the
beam, which stops the green machining process. The green machining in the absence of
ADSM is explained by the superficial vaporisation of the grains of alumina in the zone
irradiated by the beam which creates stresses causing the structure to explode locally.
Example 2
Green machining of a fine zircon by Nd :YVO laser
Unlike the alumina P172 used in the preceding example, tests of green machining on
pressed tablets of zircon (Tosoh Y-TZP) have revealed the impossibility of machining
without ADSM.
Machining of the zircon by incorporation of ADSM of the graphite type.
The recipe which enabled the green machining is similar to that of alumina: 100 g of zircon
(d50 = 200 nm) are dispersed in 100 g demineralised water in which 1 g of PEG 2000 was
previously dissolved. 14 g of Aquadag (d90 < 5 μm) are then added to the suspension, then
the whole mixture is homogenised for 30 min in the presence of grinding media. The
suspension is then dried by freeze-drying or by rotary evaporator which gives 2.4 % by
weight of carbon relative to the dry mixture. The powder obtained is pressed in the form of
tablets of 25 mm diameter under a uniaxial pressure of 40 MPa, then the tablets are
isostatically post-compacted at 175 MPa.
The green tablets obtained are then machined by laser from the same marking station as in
the previous example. The optimum lasing parameters obtained on the basis of a parametric
study are similar to those obtained for alumina, namely 40 % - 80 % of nominal power, a
working frequency of 40 - 80 kHz, a sweep speed of 100 - 6000 mm/s, an interval between
pulses of 1 to 5 μs and pulse durations between 8 and 17 ns. The machining is performed
based on a CAD file of format .dxf for example.
At the wavelength of 1.06 μm of the laser radiation, zircon has an absorptivity of 0.2 whilst
that of graphite is of the order of 0.9.
Again, very high rates of removal of material were able to be recorded (> 50 mm / min) to
depths of several mm.
In this case too, no apparent limit for the depth other than the aspect ratio of the machined
zones was noted. Various machining patterns have been implemented involving the creation
of fine and/or rough details. The machining precision proved to be of the order of the size of
the laser beam at the focal length.
After elimination of the residual carbon in air and natural sintering of the machined parts, no
apparent defect was noted.
The machined surfaces observed under a scanning electron microscope revealed no crack,
no porosity, nor any layer of redeposited molten material.
Certain untreated tablets were stored in air for several days, then machined. The same
behaviour during machining was noted as on the original tablets - proof of the absence of
ageing of the tablets. For long periods of storage of pressed parts, on the other hand, said
parts could be placed in an airtight space in the presence of a desiccant in order to avoid
humidification thereof by the ambient air.
Example 3
Green machining of a fine alumina by 3D laser
A mixed powder of fine alumina P172SB from Pechiney was prepared containing 10 % by
volume (or approximately 4 % by weight) of carbon (Aquadag) according to the procedure
illustrated in Example 1. Tablets of 25 mm diameter were pressed by uniaxial pressing at a
load of 40 MPa. These tablets were then treated by pulsed Nd:YAG laser of the nanosecond
type provided with a galvanometric head and 5 motorised spindles (3 cartesian spindles and
2 rotatable spindles ). A CAD plan of a radial microturbine was edited and the object was
reproduced by micromachining using the parameters detailed in Example 1. Each of the
turbine blades was produced one after the other by successive rotation of the tablet. In this
example, the machining time of the microturbine is of the order of 20 min. The elimination of
the graphite and the sintering of the object were performed according to the procedure of
Example 1.
The result obtained is presented in Figure 4 which illustrates the machined microturbine after
elimination of the ADSM and sintering. The object obtained is devoid of apparent defects
(crack, porosity...) and the part after sintering is totally dense.
Example 4
3D green laser machining of zircon
Pressed tablets obtained on the basis of the procedure of Example 2 were machined layer
by layer, each layer corresponding to a specific machining plan. The machining of the
pyramids shown in Figure 5 takes 20 min. The top of the obelisk below the letters Z and E
has a cross-section of the order of 50 μm, hardly more than the size of the beam at the focal
distance.
Figure 6 shows a machined tablet after elimination of the ADSM and sintering. As can be
seen, after sintering no geometric distortion of the part is noted. The machined pyramids as
well as the obelisk are intact and devoid of apparent defects.
It should be understood that the present invention is in no way limited to the embodiments
described above and that modifications can be made thereto within the scope of the
appended claims.
Claims (10)
1. Method for manufacturing ceramic parts comprising - implementation of a ceramic particle mixture, as components, a predominant portion 5 by weight of sinterable particles made of a ceramic material and particles of at least one additive, at least one of said at least one additive being a solid inorganic material, wherein said inorganic solid material is absorbent for laser radiation emitting a predetermined energy flow at a predetermined wavelength, and at this wavelength has a specific absorptivity greater than that of the other components of the ceramic mixture, in that said ceramic mixture 10 contains the particles of absorbent inorganic solid matter in the dispersed state, in proportions of less than 5 % by weight and more than 0 % by weight of the dry mixture, and in that the method further comprises - green shaping of this ceramic mixture and obtaining a dry green ceramic blank, - green machining of the green ceramic blank, by removal of ceramic material, by its 15 exposure to said pulsed laser radiation emitting a predetermined energy flow at said predetermined wavelength, and - during said exposure to this laser radiation, direct selective absorption of the laser radiation energy by the particles of absorbent dispersed inorganic solid material which degrade abruptly, with gaseous emission, local dislocation of ceramic material from 20 the green ceramic blank, ejection of this dislocated ceramic material and obtaining a machined ceramic part in the green state.
2. Method according to Claim 1, wherein the particles of the components are mixed by dry means, forming a powder.
3. Method according to Claim 1, wherein the particles of the components are put in suspension in a liquid suspension medium.
4. Method according to any one of Claims 1 to 3, wherein the green shaping is 30 performed by extrusion, casting or pressing of the ceramic mixture used.
5. Method according to any of Claims 1 to 4, wherein the pulsed laser radiation has a wavelength of 200 nm to 3 μm. 35
6. Method according to Claim 5, wherein the pulsed laser radiation has a wavelength of 900 nm to 1100 nm.
7. Method according to any one of Claims 1 to 6, wherein the pulsed laser radiation has pulse durations less than 150 ns.
8. Method according to any one of Claims 1 to 7, further comprising, after green 5 machining, sintering of the particles of ceramic material of the green machined ceramic part.
9. Method according to Claim 8, comprising, before the sintering, elimination of the absorbent dispersed solid material outside the green machined ceramic part by thermal stress thereon at a degradation temperature of this material.
10. Method according to any of Claims 1 to 9, wherein the green machining takes place at ambient pressure, in air. 5 FIG. 6
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP11168493 | 2011-06-01 | ||
EP11168493.2 | 2011-06-01 | ||
PCT/EP2012/060261 WO2012164025A1 (en) | 2011-06-01 | 2012-05-31 | Ceramic particle mixture, and method for manufacturing ceramic parts from such a mixture |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ618857A NZ618857A (en) | 2016-03-31 |
NZ618857B2 true NZ618857B2 (en) | 2016-07-01 |
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